IONIZING RADIATIONS: EFFECTS ON EMBRYO, FETUS 25 



The embryo, in contrast with the aduh, has powers of reoroaniziny; its re- 

 sidual and surviving cells so that topographic normality may be achieved. 

 However, every such indi\idual will be deficient, either in parts or in the 

 stunting of the whole. 



Deficiencies are seldom similar in litter mates, owing to the submicro- 

 scopic nature of ionizing radiations, the genetic \ariations in individuals, 

 the \arying abilities for restitution, and probably other factors. 



Irradiation of the embryo is the only way to produce irradiation congenital 

 anomalies, but such anomalies may be produced by other traumatic means. 

 Following organogenesis, irradiation efTects are similar to those one expects 

 in the adult. 



The embryo after a certain stage possesses gonad primordia or developing 

 gonads, and these are subject to irradiation effects which may not be evident 

 for generations. 



Central nervous system anomalies may be produced by irradiation of the 

 mature gamete of either sex, the fertilized egg, or any stage in development 

 prior to completion ot neurogenesis. Some formati\e cells are present even 

 after the birth of the mammal. The range of radiosensitivity of gamete to 

 formed organism is such that discussion of threshold is meaningless. We can- 

 not now state the extent or the duration of irradiation damage to the de- 

 veloping central nervous system. There may well be subtle effects to be 

 revealed by population studies o\er generations. Any exposure of the early 

 embryo should be regarded as too much. 



Finally. I would like to make four specific requests: 



1 . l^hat we insist on better and more adequate controls in radiobiology. 



2. That radiation dosimetry in all radiobiologic experiments be checked 

 by a qualified radiophysicist and be fully reported. 



3. That there be a pool of research information on neurologic effects, in- 

 cluding critically reviewed information fiom the U.S.S.R. because of the 

 language barrier. 



4. That symposia of this sort be organized as frequently as the accelerat- 

 ing accumulation of data demands. 



References 



Brues, .\. M. (ed.) 1959. Low-k-\el irradiation. Publ. Am. A'isoc. Advance. Sci. 59. 



Gentry. J. T.. Parkhurst, E., and Bulin, G. V. 1959. .\n epidemiological study of con- 

 genital malformations in New York State. Am. J. Public Health 49, 1-22. 



Green, E. L. 1959. Genetic efTects in low-lc\fl irradiation. Pub!. Am. A^wc. Advance. 

 Sci. 59. 



Hammer-Jacobson. E. 1959. Therapeutic abortion on account of x-ray examination 

 during pregnancy. Danish Med. Bull. 6, 113-121. 



